A tunable laser system is provided. The tunable laser system includes a light source, a grating, a corner mirror array, and a receiver. In which, the light source emits a beam, and the grating is located in front of the light source for reflecting the beam to form a first reflective beam. Also, the corner mirror array is located in front of the grating for receiving the first reflective beam and forms a second reflective beam accordingly. In addition, the receiver is used to receive a third reflective beam formed from reflecting the second reflective beam through the grating.